Driveline cable assembly

ABSTRACT

A blood pump assembly includes a blood pump configured for implantation and a cable assembly for providing power and control signals to the blood pump. The cable assembly includes a strain relief assembly and a driveline. The strain relief assembly secures the cable assembly to the blood pump and has an outer surface that is curved along a longitudinal extent of the strain relief assembly at least along an outer peripheral side of the outer surface. The strain relief assembly defines a compartment and an internal passage that leads to the compartment. The driveline houses a plurality of conductors that extend from the driveline through the internal passage and into the compartment.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. Ser. No. 13/747,741filed Jan. 23, 2013 (Allowed); which application claims the benefit ofU.S. Provisional Appln. No. 61/589,929 filed Jan. 24, 2012. The fulldisclosures which are incorporated herein by reference in their entiretyfor all purposes.

FIELD

This description relates to driveline cable assemblies, for example,driveline cable assemblies for ventricular assist devices.

BACKGROUND

Ventricular assist devices, known as VADs, are blood pumps used for bothshort-term and long-term applications where a patient's heart isincapable of providing adequate circulation. A VAD can supplement a weakheart or can effectively replace the natural heart's function. Forexample, a patient suffering from heart failure may use a VAD while thepatient awaits a heart transplant. In another example, a patient may usea VAD while the patient recovers from heart surgery. Some heart failurepatients may have a VAD implanted for permanent use. VADs can beimplanted in the patient's body and powered by an electrical powersource outside the patient's body through a driveline cable assembly.

SUMMARY

In one general aspect, a blood pump system includes a strain reliefassembly. The strain relief assembly includes a first member thatdefines a compartment and a second member that is more flexible than thefirst member. An outer side of the second member is curved and thesecond member defines an internal channel that leads to the compartment.

In a further aspect, according to any of the aspects above, the strainrelief assembly is sized and positioned to lie entirely within atransverse footprint of the blood pump. The blood pump has an outletportion that defines a fluid outlet axis and the strain relief assemblyorients a driveline in a direction substantially parallel to the outletaxis.

In a further aspect, according to any of the aspects above, a cableincluding electrical conductors and an internal strength member extendthrough the internal channel into the compartment. The electricalconductors engage electrical connectors of the blood pump within thecompartment, and the internal strength member is anchored to the strainrelief assembly within the compartment.

In a further aspect, according to any of the aspects above, the internalpassage has a substantially constant diameter along the longitudinalextent of the second member, and the second member has a wall thicknessthat decreases along the longitudinal extent.

In a further aspect, according to any of the aspects above, the firstmember has an annular portion that has an inner surface and an outersurface. The second member is molded about the outer surface of theannular portion. Holes are defined through the annular portion and thesecond member extends through the holes.

In a further aspect, according to any of the aspects above, the firstmember includes a surface oriented perpendicular to the internal passageconfigured to engage a cable to limit travel of the cable through thepassage.

In a further aspect, according to any of the aspects above, across-section of the second member has a substantially D-shaped exteriorat a proximal end region of the second member. A cross-section of thesecond member has a circular exterior at a distal end region of thesecond member. The second member has a wall thickness that graduallydecreases between the proximal end region and the distal end region.

In one general aspect, a blood pump assembly includes a blood pumpconfigured for implantation, and a cable assembly secured to the bloodpump for providing power and control signals to the blood pump. Thecable assembly includes a strain relief assembly and a driveline. Thestrain relief assembly secures the cable assembly to the blood pump andhas an outer surface that is curved along a longitudinal extent of thestrain relief assembly, at least along an outer peripheral side of theouter surface. The strain relief assembly defines a compartment and aninternal passage that leads to the compartment. The driveline houses aplurality of conductors that extend from the driveline through theinternal passage and into the compartment.

Implementations may include one or more of the following features. Forexample, the strain relief assembly is sized and positioned to lieentirely within a transverse footprint of the blood pump. The outersurface of the strain relief assembly has an inner peripheral sideopposite the outer peripheral side, the inner peripheral side facing theblood pump and being spaced apart from the blood pump. The blood pumphas an outer surface facing the inner peripheral side, and the innerperipheral side has a radius of curvature along the longitudinal extentthat is larger than a radius of curvature of the outer surface of theblood pump along the longitudinal extent. The pump housing includeselectrical connectors that extend into the compartment. The conductorsare electrically connected to the electrical connectors of the pumphousing, the conductors being oriented substantially transverse to theelectrical connectors. The conductors are secured within the compartmentby potting. The cable assembly includes an inner strength member thatextends through the internal passage and is anchored to the strainrelief assembly within the compartment. The blood pump has an outletportion that defines an outlet axis and the cable assembly orients thedriveline in a direction substantially parallel to the outlet axis, andthe driveline is radially offset from the outlet portion by a distanceof less than approximately 1 inch.

In one general aspect, an implantable strain relief assembly includes afirst member that has an annular portion and an opening defined throughthe annular portion. The first member has a conductor mounting portionthat defines a compartment in communication with the opening. Theimplantable strain relief assembly includes a second member that is moreflexible than the first member. The second member has an end regioncoupled to the annular portion and has an outer surface that is curvedalong a longitudinal extent of the second member at least along a sideof the outer surface. The second member defines an internal passagealong the longitudinal extent leading to the opening defined through theannular portion of the first member. The internal passage has asubstantially constant diameter along the longitudinal extent, and thesecond member has a wall thickness that decreases along the longitudinalextent.

Implementations may include one or more of the following features. Forexample, the annular portion has an inner surface and an outer surface,and the second member is molded about the outer surface. Holes aredefined through the annular portion, and the second member extendsthrough the holes. The first member is configured to receive an anchorcomponent in the compartment, and the anchor compartment is configuredto secure an end of a cable to the first member. The first memberincludes a surface oriented perpendicular to the internal passageconfigured to engage a cable to limit travel of the cable through thepassage.

In one general aspect, an implantable strain relief device includes amember having an outer surface that is curved along a longitudinalextent of the member at least along a side of the outer surface. Themember defines an internal passage along the longitudinal extent havinga substantially constant diameter along the longitudinal extent. Themember has a wall thickness that decreases along the longitudinalextent, and at least a portion of the outer surface has across-sectional geometry that includes a rounded portion opposite asubstantially flat portion.

Implementations may include one or more of the following features. Forexample, the outer surface is curved in an unloaded state of the member.The member has a distal end portion that has a cross-sectional geometrythat is substantially circular. The outer surface of the member has aside that has a radius of curvature of between approximately 1 andapproximately 3 inches along the longitudinal extent. A length of themember along the longitudinal extent is between approximately 2 andapproximately 4 inches.

Various aspects of the invention are directed to a strain reliefassembly comprising any of the features above in any combination.

In one general aspect, a method of providing strain relief at a bloodpump includes forming a strain relief assembly having a curvature alonga longitudinal extent of the strain relief assembly, positioning adriveline within the strain relief assembly, and connecting the strainrelief assembly and the driveline to the blood pump at an outer wall ofthe blood pump that connects first and second opposing surfaces of theblood pump.

Implementations may include one or more of the following features. Forexample, connecting the strain relief assembly and the drivelineincludes orienting the strain relief assembly such that electricalconnectors on the blood pump extend into a compartment defined by thestrain relief assembly. The method includes establishing an electricalconnection between conductors of the driveline and the electricalconnectors in the compartment.

In one general aspect, a blood pump assembly includes a pump housinghaving an outer surface and defining a hermetically sealed compartment.The blood pump assembly includes a boss that extends from the outersurface of the pump housing and a feed-through component coupled to theboss. The feed-through component has electrical conductors that extendoutward from the boss in a direction substantially perpendicular to theouter surface. The electrical conductors are configured to transmitelectrical signals between the hermetically sealed compartment and alocation outside the hermetically sealed compartment. The boss includesone or more attachment features configured to secure a driveline to thepump housing.

Implementations may include one or more of the following features. Forexample, a strain relief assembly engaged to the attachment features ofthe boss, the strain relief assembly defining a compartment and anopening that admits the electrical conductors into the compartment. Adriveline extending through the strain relief assembly, the drivelinehaving driveline conductors connected to the electrical conductorsthrough ferrules. The connections of the ferrules with the drivelineconductors and the electrical conductors are surrounded by potting, andthe potting has at least one exposed side. The potting is exposed at aside facing away from the pump housing. The attachment features of theboss include one or more grooves defined in the boss, and the strainrelief assembly includes one or more tabs located in the one or moretabs. The outer surface of the pump housing is substantiallycylindrical, and the electrical conductors of the pump housing extendfrom the boss in a direction radially outward from the outer surface.The driveline includes an inner strength member coupled to the stressrelief assembly through an anchor, the inner strength member beingconfigured to transmit axial loads on the driveline to the stress reliefassembly through the anchor.

Various aspects of the invention are directed to a method ofmanufacturing a strain relief assembly including forming a first memberthat defines a compartment; forming a second member that is moreflexible than the first member and having an outer side that is curved,wherein the second member defines an internal channel that leads to thecompartment. The method may include sizing and positioning the strainrelief assembly to lie entirely within a transverse footprint of anassociated implantable blood pump. The blood pump may have an outletportion that defines a fluid outlet axis. The method may includeorienting the strain relief assembly such that a driveline is in adirection substantially parallel to the outlet axis. Various aspects ofthe invention are directed to using an implantable pump including:positioning an implantable pump having a strain relief assemblyaccording to any of the above in a body, and controlling the pump topump blood from the heart to the circulatory system.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a blood pump assembly implanted at a heart.

FIG. 1B is a bottom view of the blood pump assembly implanted at theheart.

FIG. 2 is a perspective view of the blood pump assembly.

FIG. 3 is an exploded perspective view of the blood pump assembly.

FIG. 4A is a perspective view of a flexible member of the blood pumpassembly.

FIG. 4B is a top view of the blood pump assembly.

FIG. 4C is a cross-sectional view of the flexible member taken at line4C-4C of FIG. 4A.

FIG. 4D is a cross-sectional view of the flexible member taken at line4D-4D of FIG. 4A.

FIG. 4E is a cross-sectional view of the flexible member taken at line4E-4E of FIG. 4A.

FIG. 5A is a proximal end view of the flexible member.

FIG. 5B is a perspective view of the flexible member.

FIG. 6A is perspective view of a rigid member of the blood pumpassembly.

FIG. 6B is a lateral view of the rigid member.

FIG. 6C is a top view of the rigid member.

FIG. 7A is a perspective view of a strain relief assembly of the bloodpump assembly.

FIG. 7B is a cutaway view of the strain relief assembly.

FIG. 8A is an exploded perspective view of a proximal end of a drivelineof the blood pump assembly and ferrules.

FIG. 8B is a cross-sectional view of a conductor of the drivelineattached to one of the ferrules.

FIG. 9 is top view of conductors of the driveline arranged within therigid member.

FIG. 10A is an exploded perspective view of a boss of the pump housingand a feed-through component.

FIG. 10B is a perspective view of the boss and the feed-throughcomponent.

FIGS. 11A and 11B are views illustrating engagement of the rigid memberwith the boss.

FIG. 12 is a perspective view illustrating engagement of screws with therigid member and the pump housing.

FIG. 13A is a top view of a ferrule carrier.

FIG. 13B is a top view of the ferrule carrier engaged within the rigidmember.

FIG. 14A is a cross-sectional view of one of the conductors of thedriveline, one of the ferrules, and the feed-through component.

FIG. 14B is a side cutaway view of the strain relief assembly and thedriveline connected to the pump housing.

FIGS. 15A, 15B, and 15C perspective views illustrating installation ofan anchor.

FIG. 15D is a perspective view illustrating potting within the rigidmember.

FIG. 16 is an illustration of various examples of radial thicknessratios of the flexible member.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

DETAILED DESCRIPTION

Referring to FIGS. 1A and 1B, a blood pump assembly 15 can be implantedin a patient's body to supplement, or in some instances replace, thenatural pumping function of a heart 10. The blood pump assembly 15includes a blood pump 20 that is sized to be implanted in a patient'sthoracic cavity, and a cable assembly 400 that is secured to the bloodpump 20 for providing power and control signals to the blood pump 20.The cable assembly 400 includes a driveline 22 and a strain reliefassembly 24. The driveline 22 houses conductors that carry the power andcontrol signals. The strain relief assembly 24 secures the cableassembly 400 to the blood pump 20 and reinforces the driveline 22 toresist acute and chronic loading on the cable assembly 400.

The strain relief assembly 24 is curved in its unloaded state, that is,it is curved in its formed state without an applied bending force. Forexample, the strain relief assembly 24 is curved along its longitudinalextent, E, at least along an outer peripheral side 27 of an outersurface 25 of the strain relief assembly 24, for example, having asimilar curvature as the pump housing circumferentially along the sidefacing away from the blood pump 20. In some implementations, the outersurface 25 is curved along at least the majority of the longitudinalextent, E, and the curvature extends away from the blood pump 20 to adistal end of the strain relief assembly 24.

During implantation of the blood pump assembly 15 and subsequentoperation, the connection between the blood pump 20 and the driveline 22is subject to a variety of stresses. The strain relief assembly 24establishes a mechanical connection between the blood pump 20 and thedriveline 22, strengthening and protecting the driveline 22 (and itselectrical connections) against bending, twisting, and other loads(including flexural fatigue). As discussed further below, the mountinglocation and the curvature of the strain relief assembly 24 contributeto providing a low profile for the blood pump assembly 15, whichfacilitates placement in a body cavity constrained by, for example, thepatient's ribs, diaphragm, and lungs. The low profile can be achieved byminimizing a height, H, of the blood pump assembly 15 and a width, W, ofthe blood pump assembly 15 while maintaining sufficient strength towithstand the long-term stresses of implantation.

In use, the blood pump 20 receives blood through an inflow cannula 26 ofthe blood pump assembly 15 that extends into, for example, a leftventricle 12 of the heart 10. The blood pump 20 supplies blood to thecirculatory system of the patient, for example, to an aorta or aperipheral artery or peripheral vein. The outflow can be directedthrough an outflow cannula (not shown), attached at an outlet portion 28of the blood pump 20. The blood pump assembly 15 can also be implantedsuch that the blood pump 20 receives blood from a right ventricle of theheart 10 and supplies blood to, for example, a pulmonary artery. Theblood pump 20 can also be used for biventricular support with a secondblood pump 20 or a blood pump of another type.

In some implementations, as shown in FIG. 1B, the strain relief assembly24 orients the driveline 22 such that, without an applied load on thedriveline 22, at least a portion of the driveline 22 extendssubstantially parallel to an outlet axis, Y, defined by the outletportion 28 of the blood pump 20. For example, a portion 22 a of thedriveline 22 that extends outward from the strain relief assembly 24extends along an axis parallel to the outlet axis, Y. In someimplementations, the portion 22 a may be substantially parallel to theoutlet axis, Y, by extending along an axis that is within about 20degrees or within about 10 degrees of the outlet axis, Y. The strainrelief assembly 24 positions the portion 22 a at a radial offset, O_(R),from the outlet portion 28 of, for example, less than approximately 1inch, or between approximately 0.25 and approximately 0.50 inches. Inthis orientation, the strain relief assembly 24 has a curvature aboutthe blood pump 20 that is similar to the curvature of the outercircumference of the blood pump 20, and the driveline 22 is orientedparallel to the outlet portion 28 and extends from the blood pump 20 inthe same direction as the outlet portion 28. This orientation promotesanatomical efficiency in placement of the blood pump 20 by reducing thespace that needs to be created in the thoracic cavity to accommodatedifferent extensions from the blood pump 20.

Different relative positions of the outlet portion 28 and the driveline22 can facilitate other implantation techniques. For example, for a leftthoracotomy or for some minimally invasive approaches, the outflow ofthe pump 20 is oriented toward the descending aorta during implantation.To accommodate this placement of the blood pump 20, the strain reliefassembly 24 orients the driveline 22 in a direction opposite the outletportion, for example, extending from an opposite side of the blood pump20 rather than from the same side. In this configuration, the driveline22 extends along an axis substantially parallel to the outlet axisdefined by the outlet portion 28, but in an opposite direction on anopposite side of the blood pump 20.

Referring to FIG. 2, the blood pump 20 includes a pump housing 30 thatcontains a motor (not shown). The pump housing 30 includes an upperportion 32 and a bottom cover 34 welded together to form a hermeticallysealed compartment about the motor. The upper portion 32 of the pumphousing 30 has a top surface 36 opposing a bottom surface 37 of thebottom cover 34. The upper portion 32 also includes an outer wall 38 towhich the strain relief assembly 24 is mounted. The outer wall 38 can bea curved circumferential surface, for example, a generally cylindricalshape. The inflow cannula 26 extends from the top surface 36 of the pumphousing 30, in a direction generally perpendicular to the top surface36.

To attach the blood pump 20 to the heart 10, an anchoring component suchas a sewing ring (not shown) can be attached to cardiac tissue. Theinflow cannula 26 is inserted through an opening in the sewing ring andthrough an opening in the cardiac tissue. The sewing ring is thenfastened about the inflow cannula 26 with a clamp or other fastener.Various methods and apparatuses for such anchoring are disclosed in U.S.patent application Ser. No. 12/650,017, filed Dec. 30, 2009, and U.S.patent application Ser. No. 61/448,434, filed on Mar. 2, 2011, each ofwhich are hereby incorporated herein by reference for all purposes.

The driveline 22 attaches to the blood pump 20 on the outer wall 38 ofthe pump housing 30. The strain relief assembly 24 curvescircumferentially about a portion of the outer wall 38, along thecircumference of the pump housing 30, minimizing the increase in theoverall width, W, of the blood pump assembly 15 from the addition of thedriveline 22. The strain relief assembly 24 and the pump housing 30 liewithin a plane, P, generally perpendicular to an inflow axis, I, definedby the inflow cannula 26 with the strain relief assembly 24 positionedto be within a transverse footprint of the pump housing 30 to limit anyincrease in the overall height, H, of the pump housing 30. To limitpotential abrasion caused by contact between the strain relief assembly24 and the outer wall 38 of the pump housing 30, the strain reliefassembly 24 can be spaced from the outer wall 38.

Referring to FIG. 3, exemplary strain relief assembly 24 includes afirst, rigid member 200 and a second, flexible member 100 that is moreflexible than the rigid member 200. As described further below, thestrain relief assembly 24 is formed by coupling the flexible member 100to the rigid member 200, for example, by molding the flexible member 100onto a portion 202 of the rigid member 200. An end portion 60 of thedriveline 22 is secured within the strain relief assembly 24, and thecable assembly 400 is connected to the pump housing 30 to formmechanical and electrical connections to the pump housing 30. Theflexible member 100 limits stresses on the driveline 22 and distributesforces away from the connection of the driveline 22 with the blood pump20.

To form the mechanical and electrical connections, the rigid member 200attaches to a boss 300 (e.g., a protruding feature) of the pump housing30, with electrical contact pins 320 of the boss 300 extending into acompartment 210 defined in the rigid member 200. Conductors 62 housedwithin the driveline 22 also extend into the compartment 210 and areelectrically connected to the pins 320. Other components, includingferrules 64, a ferrule carrier 90, and an anchor 95, each describedfurther below, are also received in the compartment 210.

After the electrical and mechanical connections are established,potting, such as an epoxy, is introduced into the compartment 210 tosecure the connections. The potting cures to form a potting plug 500that secures the terminations of the driveline 22. When movement of thedriveline 22 occurs, the potting plug 500 transmits loads on theconductors 62 to the strain relief assembly 24 rather than permittingthe load to be transmitted through the conductors 62, ferrules 64, andpins 320. The potting that forms the potting plug 500 also becomesentangled with fibrous components of the driveline 22, such as a mesh orbraided armor layer 282, which further strengthens the mechanicalconnection between the driveline 22 and the blood pump 20. In variousembodiments, the potting plug is formed as a distinct unit from thedriveline and pump housing. In various embodiments, the potting plug 500limits moisture ingress that might otherwise result in undesiredelectrical connections between the pins 320 or between the pins 320 andmetal components of the pump assembly, such as the pump housing 30. Invarious embodiments, the potting plug is configured to electricallyisolate the internal components.

Referring to FIG. 4A, the flexible member 100 of the strain reliefassembly 24 is dimensioned to protect the end region 60 of the driveline22. The flexible member 100 fits over the driveline 22 and limitsbending and twisting of the driveline 22. The flexible member 100 isformed to withstand stresses of long-term implantation that occurduring, for example, an implantation period of five years, ten years, orlonger. Over such periods, postural changes of a patient can result inmore than one million loading cycles, more than two million loadingcycles, or more. The flexible member 100 is also formed to withstandother in-vivo stresses that occur due to, for example, cardiaccontractions and respiration of the patient. The flexible member 100 isalso designed to withstand other stresses, such as weight gain or weightloss of the patient and traumatic driveline events such as accidents.The flexible member can also be configured to provide damping,electrical resistance, and/or shock resistance for the internalcomponents. The flexible member thus can be selected and configured toachieve desired properties for a number of purposes as will be furtherdescribed below.

The flexible member 100 is formed of a resilient material, for example,silicone, a silicone copolymer, or another polymer material. Liquidsilicone rubber (LSR) silicone or high consistency rubber (HCR) siliconecan be used. Flexible member 100 may be formed of other materials aswould be understood by one of skill in the art from the descriptionherein including, but not limited to, copolymers (e.g. polyurethanesilicone, polycarbonate urethane silicone, and polyetherurethanesilicone), elastomers, and thermoplastic elastomers (TPE). Suitable TPEsinclude, but are not limited to, polyether block amides such as PEBA andPEBAX. The material properties can also be modified by the use ofvarious manufacturing techniques and treatments such as doping, theaddition of various treatment agents, thermal treatments, and the like.The resilient material of the flexible member 100 can have one or moreof the following material properties: durometer of approximately 20 toapproximately 70 Shore A, or durometer of approximately 40 toapproximately 60 shore A; tear strength of greater than approximately 40kilonewtons per meter (kN/m), or tear strength of greater thanapproximately 50 kN/m; tensile strength of greater than 8 megapascals(MPa), or tensile strength of greater than approximately 10 MPa; andelongation at break of greater than 500%.

The flexible member 100 has a longitudinal extent or length, L, betweena proximal end 102 and a distal end 104. In some implementations, thelength, L, is between approximately 0.25 inches and approximately 4inches. When the flexible member 100 is coupled to the rigid member 200,the length, L, extends along the longitudinal extent, E, of the strainrelief assembly 24 (not shown). The flexible member 100 also has anouter surface 105, which forms the outer surface 25 of the strain reliefassembly 24. When the flexible member 100 is coupled to the blood pump20, a surface 106 of the flexible member 100 faces toward the outer wall38 of the pump housing 30, and the surface 27 of the flexible member 100faces away from the outer wall 38. In some implementations, the flexiblemember 100 is sized such that it extends between approximately 45degrees to approximately 180 degrees about the circumference of theouter wall 38 of the pump housing 30 when the strain relief assembly 24is coupled to the pump housing 30.

Referring to FIG. 4B, exemplary flexible member 100 is curved along thelength, L, at least along the surface 27. The surface 106 can also becurved along the length, L. The flexible member 100 can extend about theouter wall 38 of the pump housing 30, generally tracking the curvatureof the outer wall 38. In some implementations, the surface 27 of theflexible member 100 has a radius of curvature along the length, L, ofapproximately 0.5 to approximately 4 inches, or between approximately 1and approximately 3 inches, or approximately 2 inches. The surface 106,as well as the general shape of the flexible member 100, can be formedto have a radius of curvature selected from the ranges and valuesdescribed for the surface 27. In some implementations, the surface 106is curved along at least a majority of the length, L, or along theentire length, L. The curvature may extend to the proximal end 102and/or the distal end 104.

The radius of curvature of the flexible member 100 is greater than aradius of curvature of the outer wall 38 of the pump housing 30. Whenattached to the blood pump 20, the spacing, S, between the surface 106of the flexible member 100 and the pump housing 30 increases from theproximal end 102 to the distal end 104. At the proximal end 102, thespace, S, can be approximately 0.1 inches or less. At the distal end104, the space, S, can be between approximately 0.2 inches andapproximately 1 inch, or more particularly, between approximately 0.4inches and approximately 0.6 inches.

Referring again to FIG. 4A, exemplary flexible member 100 defines aninternal passage 110 between the proximal end 102 and the distal end104, for example, through a central longitudinal axis, A, of theflexible member 100. The internal passage 110 is defined by a wall 114having a tubular inner surface 112 that has a cross-sectional diameterof between, for example, approximately 0.05 inches to approximately 0.6inches. The diameter of the internal passage 110 can be substantiallyconstant along the length, L, of the flexible member 100 (e.g., varyingless than 30%, or less than 15% along the length, L). The thickness, T,of the wall 114 measured radially outward from the tubular inner surface112 decreases or tapers along the length, L, in a direction, B, from theproximal end 102 to the distal end 104.

Because the wall 114 is thickest near the proximal end 102, resistanceto flexion at the proximal end 102 (near the connection of the driveline22 with the pump housing 30) is greater than at the distal end 104. Thethickness, T, can decrease substantially continuously along the length,L, of the flexible member 100. Consequently, the flexibility of member100 can vary along its length, L, having increasing flexibility wherethe wall thickness decreases and having decreasing flexibility where thewall thickness increases. For example, the thickness, T, can decreasewith a taper angle of for example, between approximately 1 degree toapproximately 5 degrees, or between approximately 2 degrees andapproximately 4 degrees, or at approximately 3 degrees. Because thediameter of the internal passage 110 is substantially constant along thelength, L, the outer dimensions of the flexible member 100 decreasealong the length, L, as the thickness of the wall 114 decreases.

The flexible member 100 can be non-axisymmetric, or in other words,lacks rotational symmetry about the central longitudinal axis, A. Forexample, at a proximal portion 103, the thickness of wall 114 variesabout the axis, A. As illustrated, at the proximal portion 103, thesurface 27, which faces away from the pump housing 30, is roundedcircumferentially about the axis, A, and the surface 106, which facesthe pump housing 30, is substantially flat. As described further below,the non-axisymmetric shape can contribute to increased durability andstrain relief performance compared to an axisymmetric shape. Forexample, stress and strain are decreased, and propensity for twistingwhen a lateral load is applied (e.g., in a direction parallel to theinlet axis, I, of FIG. 2) is decreased for the non-axisymmetric shapecompared to the axisymmetric shape. However, in an alternate embodiment,an axisymmetric shape may be more desirable if permitting a limiteddegree of rotation is perceived to be a benefit.

Referring to FIG. 4C, a cross-section of exemplary flexible member 100at the proximal portion 103, taken perpendicular to the axis, A,illustrates the asymmetry of the flexible member 100. The cross-sectionhas a substantially flat edge 130 at the surface 106 and a rounded edge132 at the surface 27, resulting in a D-shaped exterior. In someimplementations, at least a majority of the edge 130 is, or 80% or moreof the edge 130, is straight (e.g., linear). At corner portions 134located adjacent to the flat edge 130, a radial thickness, T₁, of thewall 114 is greater than a radial thickness, T₂, of the wall 114 at therounded edge 132. In some implementations, the thickness is increasingfrom T₁ to T₂. In some implementations the thicknesses are non-uniform.In some implementations, along a portion of the flexible member 100 oralong the entire flexible member 100, the thickness, T₁, is the largestradial thickness at a given cross-section, and the thickness, T₂, is thesmallest radial thickness at that cross-section. The greater thickness,T₁, at the corner portions 134 permits the flexible member 100 to resisttwisting and other loads more than, for example, a wall 114 with aconstant thickness equal to the thickness, T₂. Because of the locationof the flat edge 130 relative to the pump housing outer wall 38 (facinginward toward the outer wall 38), any adverse impact of the additionalthickness on the pump profile is minimized. In some implementations, theratio T₁:T₂ at the proximal end 102 is between approximately 3:1 andapproximately 10:1. In some implementations, the ratio T₁:T₂ at theproximal end 102 is between approximately 4:1 and approximately 5:1.

Referring to FIGS. 4B-4E, between the proximal end 102 and the distalend 104, the outer dimensions of the flexible member 100 transition fromhaving a D-shaped cross-sectional geometry (FIG. 4C) at the proximalportion 103 to having a substantially circular cross-sectional geometry(FIG. 4E) at a distal portion 109. A transition portion 107 of theflexible member 100 between the proximal portion 103 and the distalportion 109 (FIG. 4D) illustrates how the width, W_(F), of a flat edge140 on the surface 106 decreases, and corner regions 144 becomeincreasingly rounded.

Due to this transition along the length, L, of the flexible member 100,the ratio T₁:T₂ diminishes along the axis, A, in a direction from theproximal end 102 to the distal end 104. This ratio can be, for example,the ratio between a maximum radial thickness at a given axial positionand the minimum radial thickness at that axial position. From a maximumratio of T₁:T₂ at the proximal portion 103, the ratio is graduallyreduced to approximately 1:1 at the distal portion 109 (for example, ator near the distal end 104). As shown in FIG. 4E, the ratio of thethickness T₁:T₂ at the distal portion 109 is approximately 1:1, whichhelps uniformly distribute stress on the driveline 22 and impedestwisting of the driveline 22 when the driveline 22 is placed within theflexible component 100. The ratio T₁:T₂ can be reduced such that theratio decreases more rapidly over the proximal portion 103 than over thedistal region 109. For example, the ratio T₁:T₂ can decreaselogarithmically along the length, L, of the flexible member 100, asshown in FIG. 16. As a result, the ratio T₁:T₂ is closer to 1:1 than themaximum ratio along the majority of the length, L, of the flexiblemember 100.

In some implementations, a radial thickness, T₃, that extendsperpendicular to the substantially flat edge 130 is substantially thesame as (e.g., within 20% of, or within 10% of) the thickness, T₂, atthe same axial position along the axis, A. This relationship may occuralong a portion of or along the entire length, L, of the flexible member100. Because the thickness, T₃, is oriented radially outward from theouter wall 38 of the pump housing 30, maintaining the thickness similarto the thickness, T₂, helps reduce the overall profile of the pump 20.

In some implementations, a maximum thickness of the wall 114 is betweenapproximately 0.02 and approximately 0.08 inches, or betweenapproximately 0.04 and approximately 0.06 inches. As stated above, thethickness of the wall 114 and the shape of the flexible member 100 canbe selected to withstand more than one million loading cycles, more thantwo million loading cycles, or more, where each loading cycle includesapplication of at least one foot-pound of load to the flexible member100 while the proximal end 102 is secured. Each loading cycle caninclude axial deflection, circumferential deflection, or both. Axialdeflection can include, for example, force applied to the flexiblemember 100 along the inlet axis, I, of the blood pump 20 (see FIG. 2).Circumferential deflection can include, for example, force applied tothe flexible member 100 in a direction radially outward from the outerwall 38 of the pump housing 30.

Referring to FIGS. 5A and 5B, during the molding process, an attachmentportion 150 is formed at the proximal end 102 of the flexible member 100that captures the rigid member 200. The attachment portion 150 is formedwith an outer wall 152 and an inner wall 154 defining an annular space155 in which the annular portion 202 of the rigid member 200 is located.Between the outer wall 152 and the inner wall 154, connecting links 156extend through the annular portion 202 to lock the flexible member 100in place relative to the rigid member 200, as described further below.

The materials mentioned above that form the flexible member (e.g.,silicone and silicone copolymers) are well suited to provide strainrelief, but may not adhere well to more rigid materials. The exemplaryconnecting links 156 provide mechanical attachment of the flexiblemember 100 to the rigid member 200 in a manner that relies on thetensile strength, elongation at break, and tear strength of the materialof the flexible member 100 (e.g., silicone or silicone copolymers), thusdecreasing the risk of dislodgement of the flexible member 100 from therigid member 200.

Referring to FIG. 6A, the annular portion 202 of the rigid member 200provides attachment features over which the flexible member 100 ismolded. One or more circumferential grooves 220 are defined around theexterior of the annular portion 202, for example, betweencircumferential ridges 201 about the annular portion 202. Holes 222 aredefined radially through the annular portion 202. When the flexiblemember 100 is molded onto the rigid member 200, material flows into thegrooves 220, thereby forming rings that secure the annular portion 202to the flexible member 100, and into the holes 222, thereby forming theconnecting links 156. The material in the grooves 220 and the holes 222impede removal of the flexible member 100 from the rigid member 200 inthe event of, for example, axial loading. In some implementations, aprimer is applied to the annular portion 202 before the flexible member100 is formed, which can promote adhesion of the flexible member 100 tothe annular portion 202.

The rigid member 200 can be an integral component formed of, forexample, an implantable metal such as titanium. The rigid member 200 canbe formed of the same material as the boss 300 and the pump housing 30,thus reducing possibility for corrosion or unequal thermal expansion atthe interface of the rigid member 200 with the boss 300.

The rigid member 200 defines the compartment 210 between lateral walls211. The annular portion 202 defines an opening 212 along a centralaxis, X, leading into the compartment 210. The compartment 210 is openat a top side 213, and an opening 216 is defined at the bottom of thecompartment 210 through a bottom wall 214 of the rigid member 200. Theopening 216 is located such that when the rigid member 200 is attachedto the boss 300, the opening 216 is disposed over the electricallyconductive pins 320. The lateral walls 211 and the bottom wall 214 forma conductor mounting portion in which electrical connections with theconductors 62 are established.

The lateral wall 211 from which the annular portion 202 extends includesan outer surface 211 a that is oriented perpendicular to the axis, X,and extends completely about the annular portion 202. During molding ofthe flexible member 100 onto the annular portion 202, the outer surface211 a and an opposite inner surface 211 b act as shut-offs against whichthe proximal end 102 of the flexible member 100 is formed. In someimplementations, an optional layer 180 of the flexible member 100 can bemolded on the inner surface 211 b (see FIG. 12).

Referring also to FIG. 6B, the rigid member 200 includes extensions ortabs 230, 232 that engage the boss 300 to connect the rigid member 200to the boss 300. The tab 230 extends from a proximal end 231 of therigid member 200, which is located opposite the annular portion 202. Forexample, the tab 232 is located on the bottom of the rigid member 200,underneath the compartment 210. The tab 232 is shaped as a rail andextends toward the proximal end 231 in a direction parallel to the axis,X. Above the tab 232, the rigid member 200 defines a groove 234 forattachment to the boss 300.

Referring to FIG. 6C, within the compartment 210, the rigid member 200defines holes 240 that admit the screws 80 or shear pins that limitdisengagement of the rigid member 200 from the boss 300, as describedfurther below. The holes 240 are defined through raised portions 241that extend from the bottom wall 214. Near the opening 212, the raisedportions 241 have surfaces 250 oriented perpendicular to the axis, X.The surfaces 250 are configured to engage an end of the driveline 22 tolimit travel of the driveline 22 into the compartment 210.

Also within the compartment 210, the rigid member 200 defines slots 242oriented perpendicular to the axis, X, that receive the anchor 95. Theinternal walls that define the slots 242 extend partially inward fromthe lateral walls 211, leaving an unobstructed central channel 244 inthe compartment 210 to accommodate the conductors 62 of the driveline22.

Referring to FIG. 7A, the strain relief assembly 24 includes theflexible member 100 molded onto the rigid member 200. The flexiblemember 100 defines the internal passage 110 through the opening 212 inthe annular portion 202, such that the internal passage 110 leads to thecompartment 210.

Referring to FIG. 7B, the strain relief assembly 24 receives thedriveline 22 to form the cable assembly 400 that attaches to the pumphousing 30. After a silicone adhesive or other bonding agent is appliedto the tubular inner surface 112 of the flexible member 100, thedriveline 22 is advanced through the internal passage 110. The presenceof the inner wall 154 of the flexible member 100 within the annularportion 202 facilitates bonding to the driveline 22 and cushionsinternal edges of the rigid member 200 that might otherwise impinge onthe driveline 22. The annular portion 202 has an end 203 that istapered, which reduces stress concentrations in the flexible member 100around the end 203.

Referring to FIG. 8A, the driveline 22 includes, for example, an innerstrength member 68, the conductors 62, a covering (not shown), an innerjacket 280, the armor layer 282, and an outer jacket 284. The driveline22 can include features as described in U.S. patent application Ser. No.13/314,806, filed on Dec. 8, 2011, which is hereby incorporated byreference in its entirety. The inner strength member 68 is formed, forexample, of braided ultra-high molecular weight polyethylene, or otherlightweight, flexible material with high tensile strength and providesresistance to axial breakage of the driveline 22. The conductors 62 aredisposed about the inner strength member 68, for example, wrappedhelically, wrapped in twisted pairs, or arranged in anotherconfiguration. Here, six conductors 62 are shown, but more or fewerconductors 62 can be used. The covering can be disposed about theconductors 62 to reduce friction, thereby increasing the longevity ofthe driveline 22. The covering can be formed, for example, ofpolytetrafluoroethylene (PTFE) or fluorinated ethylene propylene (FEP)and can be applied as a tape wrapped about the conductors 62. The innerjacket 280 can be extruded onto the covering as a layer of, for example,silicone or silicone copolymer. Alternatively, polycarbonate-urethane,silicone polycarbonate-urethane, or other thermoplastics and copolymerscan be used.

Located over the inner jacket 280, the armor layer 282 providesresistance to cuts, flexure failure, and other damage. The armor layer282 can be a braided material or mesh composed of, for example, aramidfibers or para-aramid fibers. The outer jacket 284 is extruded over thearmor layer 282 to form the exterior of the driveline 22. The outerjacket 284 can be formed of a silicone elastomer or other biocompatiblepolymer.

To facilitate a secure connection with the electrically conductive pins320 of the blood pump 20, the end 63 of each conductor 62 is insertedinto one of the ferrules 64. The ferrules 64 are crimped onto theelectrical conductors 62 to establish mechanical and electricallyconductive connections. The ferrules 64 can be formed of acorrosion-resistant metal, for example, platinum or a platinum-iridiumalloy. The ferrules 64 and the pins 320 can be formed of the sameelectrically-conductive material, which reduces the potential forcorrosion or differing rates of thermal expansion.

Referring to FIG. 8B, each ferrule 64 includes a chamfered end 290,which facilitates insertion of stranded wire. Along a length, L_(F), ofeach ferrule 64, the ferrule 64 defines a space 292 that receives an end63 of the conductor 62. Perpendicular to the length, L_(F), the ferrule64 also defines a space 294 that receives one of the pins 320 and aspace 296 that facilitates welding of the ferrule 64 to the pin 320.

Referring to FIG. 9, in the completed cable assembly 400, each componentof the driveline 22 extends through the internal passage 110 into thecompartment 210 of the rigid member 200. The outer jacket 284 has acircumferential end 285 that engages with the surfaces 250 setting theposition of the driveline 22 relative to the strain relief assembly 24.The armor layer 282, the inner jacket 280, and the conductor coveringterminate in the compartment 210, for example, between the raisedportions 241 of the rigid member 200. The conductors 62 are spaced apartand arranged with the ferrules 64 located over the opening 216. Theinner strength member 68 initially extends outside the compartment 210,but is later terminated within the compartment 210 after the cableassembly 400 is attached to the pump housing 30.

Referring to FIG. 10A, the boss 300 provides attachment features formechanically connecting to the cable assembly 400, for example, slots orgrooves 312, 314 that respectively receive the tabs 230, 232 of therigid member 200. The boss 300 also defines threaded holes 310 thatreceive the screws 80. The threaded holes 310 are defined only partiallythrough the boss 300 to preserve the hermetic seal of the pump housing30.

In some implementations, the boss 300 is separate from the upper portion32 of the pump housing 30 (FIG. 2). After the boss 300 is formed, theboss 300 can be welded to the outer wall 38 of the pump housing 30 toform a hermetic seal. The mechanical connection of the cable assembly400 to the boss 300 secures the cable assembly 400 to the pump housing30.

The boss 300 defines an opening 304 that receives a hermeticfeed-through component 330 that, for example, transmits electricalsignals into a hermetically sealed compartment. The boss 300 includes arecessed shelf 306 around the opening 304 that engages a flange 333 ofthe feed-through component 330. When the flange 333 is seated againstthe shelf 306, the feed-through component 330 is welded to the boss 300to form a hermetic seal around the feed-through component 330 (FIG.10B).

Forming the feed-through component 330 and the boss 300 as separatecomponents can facilitate manufacturing, as different process steps andtemperatures may be needed to form the different components. Forexample, high temperature processes can be used to form the feed-throughcomponent 330 without warping or stressing the boss 300. In addition,the separate components can facilitate assembly of the pump housing 30.For example, the boss 300 is first welded to the upper portion 32 of thepump housing 30. Electrical connections are then established between theinner pump electronics and the pins 320 before the feed-throughcomponent 330 is welded to the boss 300.

The feed-through component 330 includes the pins 320, disposed on a bodycomponent 331 that is formed of the same material as the boss 300, forexample, titanium. Electrical signals applied to the pins 320 aretransmitted through the feed-through component 330 to the motor andother electronics sealed within the pump housing 30. Thus, the pins 320are configured to transmit electrical signals between the hermeticallysealed compartment that houses the motor and a location outside thehermetically sealed compartment, for example, to the compartment 210.The pins 320 extend perpendicular to an outer surface 332 of thefeed-through component 330, in a direction that is substantiallyradially outward from outer wall 38 of the pump housing 30 (e.g., within20 degrees of, or within 10 degrees of a radial direction).

Referring to FIG. 10B, each pin 320 is surrounded by a sheath 321 thatlimits the potential for electrical shorts to the body component 331.Each sheath 321 also acts as a leak barrier, impeding moisture fromentering the space between the corresponding pin 320 and the bodycomponent 330. The sheaths 321 can be formed of ceramic, for example, analumina ceramic, a polycrystalline ceramic, or both. The sheaths 321 caneach be surrounded by a sealing layer of ceramic or ceramic componentthat forms a hermetic seal and acts as a dielectric, as describedfurther below. In some implementations, rather than forming sheathsabout individual pins 320, a portion of the body component 331 (e.g., acentral portion on which multiple pins 320 are disposed) can be formedof ceramic, glass, or another dielectric material.

A minimum spacing, S_(m), can be maintained between the sheaths 321 tomaintain desired dielectric characteristics. To minimize a width, W_(p),across which the pins 320 are positioned (while maintaining the minimumspacing, S_(m)), the pins 320 can be arranged offset from each other.For example, the pins 320 can be disposed in two rows, R₁, R₂, that areoffset from each other, for example, spaced apart by a distance, S_(w),in width and spaced apart by a distance, S_(d), in depth. By staggeringor alternating the positions of the pins 320 in this manner, a smalleroverall width, W_(p), is achieved than would be possible by aligning thepins 320 in a single row. In some implementations, more than two rows ofstaggered pins can be configured for purpose of minimizing width, W_(p).In some implementations, a single row of pins may be provided when it isnot desired to minimize the width, W_(p), and pins can alternatively beprovided in an arrangements other than in rows.

Referring to FIG. 11A, the cable assembly 400 attaches to the pumphousing 30 by engaging the boss 300. First, the rigid member 200 ispositioned with the opening 216 located over the pins 320. Movement inthe direction of arrow K causes the tab 230 to enter the groove 312 inthe boss 300. Continuing the motion of the rigid member 200 relative tothe boss 300 inserts the tab 232 in the groove 314, and simultaneouslyinserts the tab 316 of the boss 300 in the groove 234 of the rigidmember 200, reaching the orientation shown in FIG. 11B.

Referring to FIG. 11B, the cable assembly 400 is shown fully seatedagainst the boss 300. The engagement of the tabs 230, 232, 316 and thecorresponding grooves 312, 314, 234 limits removal of the cable assembly400 by forces away from the pump housing 30. The proximal end 231 of therigid member 200 engages a corresponding surface 318 of the boss 300 tolimit further travel of the rigid member 200 relative to the boss 300 inthe direction of arrow K.

Referring to FIG. 12, with the cable assembly 400 seated against theboss 300, the screws 80 are inserted to secure the position of the rigidmember 200 relative to the boss 300. The screws 80 are inserted throughthe holes 240 defined in the rigid member 200 and into the threadedholes 310 defined in the boss 300. In some implementations, shear pinscan be used in place of screws.

Referring to FIG. 13A, after the screws 80 are inserted, the ferrulecarrier 90 is placed over the ferrules 64, orienting the ferrules 64relative to each other and relative to the pins 320 that now extend intothe compartment 210. The ferrule carrier 90 is formed of an electricallynon-conductive material, such as plastic.

The ferrule carrier 90 defines parallel channels 91, 92 that receiveends of the ferrules 64. The channels 91, 92 arrange ends of theferrules 64 at alternating positions P₁, P₂, aligned with the positionsof the corresponding pins 320. The ferrule carrier 90 also spaces apartthe ferrules 64 to avoid unwanted electrical connections between theferrules 64, and secures the pins of the wires against the ferrules ontothe cable boss.

Referring to FIG. 13B, the ferrules 64 are shown being aligned by analternative ferrule carrier 90 a. The alternative ferrule carrier 90 aextends along the entire length of the ferrules 64, and positions theferrules 64 relative to each other as described above for the ferrulecarrier 90. The ferrules 64 are each engaged to the corresponding pins320 to establish electrical connections between the conductors 62 andthe blood pump 20. Each ferrule 64 receives one of the pins 320 in thespace 294 (FIG. 8B). The ferrules 64 are then welded to the pins 320while the ferrule carrier 90 maintains the proper alignment. Theferrules 64 and pins 320 can be laser welded to form an electricalconnection and a mechanical connection. After the ferrules 64 and thepins 320 are welded together, the ferrule carrier 90 a (or the ferrulecarrier 90) can be removed from the compartment 210. The welds maintainthe position of the ferrules 64 relative to the pins 320.

In some implementations, the ferrule carrier 90 remains positioned onthe ferrules 64 after the ferrules 64 and pins 320 are welded, as otherterminations are made in the compartment 210. When the terminations arecomplete, the potting plug 500 can be formed about the ferrule carrier90 such that it is secured within the compartment 210.

Referring to FIGS. 14A and 14B, the connections between the ferrules 64and the pins 320 are made in the compartment 210 of the rigid member200, with the conductors 62 and the ferrules 64 oriented perpendicularto the pins 320. By connecting the pins 320 and ferrules 64perpendicular to each other, the connections can be made within a smallradial distance, D, outward from the pump housing 30. In someimplementations, the connections can be made with a radial distance, D,from the pump housing 30 of approximately 0.225 inches or less.

On the interior of the pump housing 30, the pins 320 can be connected toa flexible printed circuit 322 that extends substantially perpendicularto the pins 320. In some implementations, the angle of the printedcircuit 322 with the pins 320 is between 70 degrees and 110 degrees, orbetween 80 degrees and 100 degrees. For example, the printed circuit 322can extend along an inner circumference of the pump housing 30 andterminate in a rigid printed circuit board-type termination. In thismanner, two 90-degree turns can be made in the conductive path, in thedistance, D, that generally corresponds to a length of the pins 320.

As shown in FIG. 14A, the feed-through component 330 includes ceramiccomponents 321 a which each provides a hermetic seal between one of thepins 320, the corresponding sheath 321, and the body component 331. Theceramic component 321 a is located at least partially within the bodycomponent 331 and extends about one of the pins 320. The ceramiccomponent 321 a also fills gaps between the sheath 321 and the pin 320,and between the sheath 321 and the body component 331. Each ceramiccomponent 321 a also acts as a dielectric, limiting the potential forelectrical shorts between the body component 331 and the pin 320extending through the ceramic component 321 a. The ceramic component 321a also impedes dendritic formations about the pins 320 that otherwisemay occur due to moisture. In some implementations, the ceramiccomponent 321 a is formed of a polycrystalline ceramic material.

The ceramic component 321 a is formed in a space 334 defined in the bodycomponent 331. Each sheath 321 is formed, for example, by machining ormilling an alumina ceramic material. To form the ceramic component 321a, the sheath 321 and the pin 320 are positioned such that the pin 320extends through the space 334 and the sheath 321 extends at leastpartially into the space 334. A ceramic powder, for example, apolycrystalline ceramic powder, is packed into the space 334 about thepin 320. The ceramic powder is heated until liquefied, permittingliquefied material to fill gaps between the sheath 321 and the pin 320,and between the sheath 321 and the body component 331. The ceramicmaterial is then cooled, and it solidifies to form the ceramic 321 athat hermetically seals the space 334. In some implementations, theceramic material of the ceramic component 321 a forms a chemical bondwith materials of the body component 331, the sheath 321, and/or the pin320. For example, a chemical bond can be formed with a titanium oxidelayer of the body component 331 and with a platinum or platinum alloymaterial of the pin 320.

As an alternative to using the sheath 321 and forming the ceramiccomponent 321 a in the body component 331, a pre-formed ceramiccomponent may be used, for example, a single ceramic component thatextends through the body component 331. After the ceramic component ispositioned about a pin 320 and within the space 334 in the bodycomponent 331, brazing can be used to hermetically seal the interfacebetween the body component 331 and the ceramic component, and alsohermetically seal the interface between the ceramic component and thepin 320. During brazing, gold, a gold alloy, or another filler materialmay be used to form wetted connections between the components.

Referring to FIG. 15A, after the electrical connections are established,the anchor 95 is placed in the compartment 210. During insertion, theanchor 95 travels radially inward toward the pump housing 30, such thattwo arms 96 of the anchor 95 are received in corresponding slots 242 ofthe rigid member 200. The anchor 95 defines a space 97 between the arms96 such that insertion of the anchor 95 does not interfere with theconductors 62 in the compartment 210. In some implementations, theanchor 95 is formed of titanium.

Referring to FIG. 15B, the anchor 95, when disposed in the slots 242,extends radially outward from outer wall 38 the pump housing 30 andsubstantially perpendicular to the internal passage 110 of the flexiblemember 100. For example, in some implementations, the angle between theanchor 95 and the pump housing 30 can be between 70 degrees and 110degrees, or between 80 degrees and 100 degrees. The anchor 95 defines anopening 98 through which the inner strength member 68 is threaded.

Referring to FIG. 15C, the inner strength member 68 is axially loaded toreduce slack, and then the inner strength member 68 is terminated in thecompartment 210. For example, the inner strength member 68 can beterminated with a knot such that an end 69 of the inner strength member68 is larger than the opening 98 in the anchor 95. Axial loads on thedriveline 22 are transmitted through the inner strength member 68 to theanchor 95, thus avoiding or reducing axial loads on the conductors 62 orthe potting plug 500, which is subsequently formed in the compartment210. As such, the anchor 95 provides a compression force to secure thewires against the cable boss in the compartment 210 and also absorbstension forces or axial loads exerted on the driveline 22 that aretransmitted through the inner strength member 68.

Referring to FIG. 15D, potting is introduced into the compartment 210 tocapture the terminations of the driveline 22. In some implementations,the potting is a UV-cured epoxy that is applied as a liquid. The pottingfills the compartment 210, surrounding the conductors 62, ferrules 64,and pins 320. The potting can be exposed to UV light or a heat cycle tocure the potting and form the potting plug 500. As further examples, thepotting can be a silicone encapsulant, a thermoset plastic material, ora two-part epoxy.

The potting plug 500 captures the ends of the armor layer 282, the innerjacket 280, the conductors 62 and all other components within thecompartment 210. The potting plug 500 maintains the positions of theconductors 62, the ferrules 64, and the pins 320 to protect theelectrical connections of the driveline 22 with the blood pump 20. Thepotting plug 500 also supports the mechanical connections of the cableassembly 400 to the pump housing 30, for example, by limiting removal ofthe screws 80 and limiting removal of the anchor 95. The potting plug500 also acts as a moisture barrier about the ferrules 64, pins 320, andelectrical connections of the driveline 22, limiting exposure toexternal elements such as blood, tissue, liquid, or air.

The potting plug 500 can be formed of a material that is transparentwhen cured. Because the compartment 210 is open in a direction facingaway from the pump housing 30, the connections within the potting plug500 can easily be visually inspected. The rigid member 200 acts as acasing or housing for the potting plug 500 formed, for example, oftitanium. In some implementations, at least one side of the potting plug500 is exposed to external elements, such as tissue and fluids. Forexample, the side of the potting plug 500 facing away from the bloodpump 20 (for example, at the opening of the compartment 210 that facesaway from the blood pump 20) is not covered by the rigid member 200 orother components of the blood pump assembly 15.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the claimed invention. For example, ratherthan using a non-axisymmetric flexible member, an axisymmetric flexiblemember (for example, one having a generally circular cross-sectionalgeometry along its length) can be used in a strain relief assembly.

In addition, the mechanisms described above can be used to electricallyand mechanically connect a driveline cable assembly to a pump that has adifferent shape than the pump 20. The same mechanisms and strain relieftechniques can be used for connections of cables to any implantedcomponent, or to a battery, controller, or other component of aventricular assist system. A driveline cable assembly can be attached atany outer surface of a pump housing. The strain relief assembly can beshaped to extend along one or more sides of the pump housing, and cangenerally track the outer contours of the pump housing. Thus the strainrelief assembly can have a shape, size, and/or radius of curvature thatmatches the outer dimensions of a corresponding pump.

Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A cable assembly for attachment to electricalpins of an implantable blood pump, the cable assembly comprising: adriveline for providing power to the implantable blood pump, thedriveline housing a plurality of conductors having a distal end; and aplurality of ferrules coupled to the distal ends of the plurality ofconductors, the plurality of ferrules configured to perpendicularlycouple the electrical pins of the implantable blood pump with theplurality of conductors of the driveline.
 2. The cable assembly of claim1, wherein the plurality of ferrules include spaces for receiving theelectrical pins of the implantable blood pump, the spaces arrangedperpendicular to the distal ends of the plurality of conductors.
 3. Thecable assembly of claim 2, further comprising a rigid member defining acompartment, the rigid member having a driveline opening leading intothe compartment for receiving the driveline and a connection opening forreceiving pins of the implantable blood pump, wherein the plurality offerrules couple to the rigid member such that the spaces for receivingthe electrical pins of the implantable blood pump are aligned with theconnection opening of the rigid member.
 4. The cable assembly of claim3, wherein the rigid member comprises an engagement feature for couplingwith the implantable blood pump.
 5. The cable assembly of claim 3,wherein each ferrule includes a welding space opposite each electricalpin receiving space, the welding spaces configured to facilitate weldingof the ferrule to the electrical pins of the implantable blood pump. 6.The cable assembly of claim 3, further comprising a ferrule carrierplaced over the plurality of ferrules, the ferrule carrier configured toorient the ferrules relative to each other.
 7. The cable assembly ofclaim 3, wherein the driveline includes an inner strength member, andwherein the cable assembly further comprises an anchor coupled to therigid member, the anchor configured to couple with the inner strengthmember of the driveline such that axial loads on the inner strengthmember are transferred to the anchor.
 8. The cable assembly of claim 7,wherein the anchor includes an opening for threading the inner strengthmember of the driveline.
 9. The cable assembly of claim 3, furthercomprising a flexible member coupled to the rigid member adjacent to thedriveline opening, the flexible member defining an internal passage forreceiving the driveline and limiting stresses on the driveline andconfigured to distribute forces away from a connection of the drivelinewith the blood pump.
 10. The cable assembly of claim 9, wherein theflexible member is curved in an unloaded state.
 11. The cable assemblyof claim 9, wherein the flexible member is molded over an annularportion of the rigid member.
 12. The cable assembly of claim 11, whereinthe annular portion of the rigid member includes a plurality of holesextending therethrough such that when the flexible member is molded overthe annular portion of the rigid member, material flows through theholes and forms connecting links that secure the flexible member to theannular portion of the rigid member.
 13. A blood pump assemblycomprising the cable assembly of claim 9 attached to the electrical pinsof the implantable blood pump, and wherein the flexible member and therigid member orient the driveline in a direction substantially parallelto an outlet axis of the implantable blood pump.
 14. A blood pumpassembly comprising the cable assembly of claim 9 attached to theelectrical pins of the implantable blood pump, and wherein the flexiblemember and the rigid member orient the driveline to extend in adirection opposite to an outlet portion of the implantable blood pump.15. A blood pump assembly comprising the cable assembly of claim 1attached to the electrical pins of the implantable blood pump, andwherein potting is applied to the attachment of the cable assembly tothe electrical pins to form a potting plug that secures the coupling ofthe driveline conductors to the pins.
 16. The blood pump assembly ofclaim 15, wherein the potting plug is transparent when cured and whereinthe potting plug has at least one exposed side, thereby allowing visualinspection of connections within the potting plug.
 17. A blood pumpassembly comprising the cable assembly of claim 1 attached to theelectrical pins of the implantable blood pump and wherein theimplantable blood pump further comprises: a pump housing having an outersurface and defining a hermetically sealed compartment; a boss thatextends from the outer surface of the pump housing; and a feed-throughcomponent coupled to the boss, the feed-through component comprising theelectrical pins of the implantable blood pump, and wherein theelectrical pins of the implantable blood pump extend outward from theboss in a direction substantially perpendicular to the outer surface,the electrical pins configured to transmit electrical signals betweenthe hermetically sealed compartment and a location outside thehermetically sealed compartment though the cable assembly, the bossincluding one or more attachment features configured to secure the cableassembly to the pump housing.
 18. A method for providing electrical andmechanical connection to a blood pump, the method comprising: forming astrain relief assembly having a curved flexible member and a rigidmember, the rigid member defining a compartment; feeding a drivelinehaving a plurality of conductors through the strain relief assembly andsecuring the conductors of the driveline within the compartment of thestrain relief assembly; connecting the strain relief assembly and thedriveline to a blood pump housing such that the plurality of conductorsof the driveline are in electrical and mechanical connection with aplurality of pins of the blood pump.
 19. The method of claim 18, whereinthe step of forming the strain relief assembly comprises molding thecurved flexible member to a portion of the rigid member.
 20. The methodof claim 18, wherein securing the conductors of the driveline within thecompartment of the strain relief assembly comprises coupling ferrules tothe conductors and securing the ferrules to the rigid member, andwherein the ferrules provide perpendicular coupling between theconductors and the pins.
 21. The method of claim 20, wherein connectingthe strain relief assembly and the driveline to the blood pump housingcomprises coupling the pins of the blood pump to the ferrules andwelding the pins and the ferrules together.
 22. The method of claim 18,wherein the driveline further comprises an inner strength member andwherein the method further comprises securing the inner strength memberof the driveline to the rigid member.
 23. The method of claim 22,wherein securing the inner strength member of the driveline to the rigidmember comprises coupling the inner strength member to an anchor andcoupling the anchor to the rigid member.
 24. The method of claim 23,wherein securing the inner strength member of the driveline to the rigidmember comprises axially loading the inner strength member of thedriveline prior to coupling the inner strength member to the anchor. 25.The method of claim 18, further comprising, after connecting the strainrelief assembly and the driveline to the blood pump housing, introducingpotting into the compartment and forming a potting plug over theelectrical and mechanical connection between the conductors and theplurality of pins of the blood pump.
 26. The method of claim 25, whereinthe potting plug is transparent when cured and wherein the potting plughas at least one exposed side, thereby allowing visual inspection ofconnections within the potting plug.
 27. A method of providing strainrelief at a blood pump, comprising: forming a strain relief assemblyhaving a curvature along a longitudinal extent of the strain reliefassembly; positioning a driveline within the strain relief assembly; andconnecting the strain relief assembly and the driveline to the bloodpump at an outer wall of the blood pump that connects first and secondopposing surfaces of the blood pump.
 28. The method of claim 27, whereinconnecting the strain relief assembly and the driveline comprisesorienting the strain relief assembly such that electrical connectors onthe blood pump extend into a compartment defined by the strain reliefassembly.
 29. The method of claim 28, further comprising establishing anelectrical connection between conductors of the driveline and theelectrical connectors in the compartment.
 30. A blood pump assemblycomprising: a pump housing having an outer surface and defining ahermetically sealed compartment; a boss that extends from the outersurface of the pump housing; and a feed-through component coupled to theboss, the feed-through component having electrical conductors thatextend outward from the boss in a direction substantially perpendicularto the outer surface, the electrical conductors being configured totransmit electrical signals between the hermetically sealed compartmentand a location outside the hermetically sealed compartment, the bossincluding one or more attachment features configured to secure adriveline to the pump housing.
 31. The blood pump assembly of claim 30,further comprising a strain relief assembly engaged to the attachmentfeatures of the boss, the strain relief assembly defining a compartmentand an opening that admits the electrical conductors into thecompartment.
 32. The blood pump assembly of claim 31, further comprisinga driveline extending through the strain relief assembly, the drivelinehaving driveline conductors connected to the electrical conductorsthrough ferrules, wherein the connections of the ferrules with thedriveline conductors and the electrical conductors are surrounded bypotting, and the potting has at least one exposed side.